When a drug must be administered to a patient over a relatively long period of time, a common procedure is to implant a drug administration portal just under the skin at a convenient location in the patient's body. The portal, an example of which is marketed by Pharmacea Inc. under its PORT-A-CATH trademark, is basically a small chamber with an outlet tube or catheter leading to a selected infusion site in the body. The portal also has an inlet passage into the chamber fitted with a needle-penetrable, self-sealing septum. When the portal is implanted, the septum is situated just under the skin so that infusate can be introduced into the portal chamber by inserting a needle or cannula connected to an infusate source, e.g. a syringe, through the patient's skin and the septum into the inlet passage.
The portal is usually implanted so that its septum is more or less parallel to the skin surface necessitating a needle penetration at a 90 degree angle to the skin. Whereas the needles commonly used to administer drugs are straight non-coring-type needles, the needles used in this application are generally modified to have a 90 degree bend approximately one-half centimeter from the needle hub to assure a 90 degree skin penetration. This configuration permits easier manipulation of the hub in order to connect the hub to a syringe or extension set which connection is usually made parallel to the patient's skin. It also facilitates taping down of the needle and associated extension to the patient and provides a lower profile which is important if the needle is to be left in place for a long period of time under the patient's clothing.
While the 90 degree-bent needle provides greater ease of use and is an improvement over a standard straight needle, it is still relatively awkward to hold when the needle is being pushed through the portal septum against the resistance presented by the septum. Also, needles with a 90 degree bend are difficult to tape down so as to provide a sterile, sealed area all around the needle exit site from the body. Still further, the profile of the needle with its hub is not particularly smooth and often not close enough to the skin because the needle point "bottoms" in the portal while the needle hub is still spaced appreciably from the patient's skin. This type of variation occurs because conventional 90 degree-bent needles are made in discrete lengths and the position of the portal under the skin may vary due to factors such as the patient's size and weight. Resultantly, when the patient moves, there is often relative movement between the needle and the patient which, over a period of time, can cause considerably discomfort to the patient and can increase the risk of infection at the penetration site of the needle.
Finally, as these prior needles are difficult to insert into the patient, they are also awkward to remove from the patient due to the inability of the physician to firmly grasp the needle in order to withdraw it from the portal and the patient.
Over the past few years various support and guide devices have been developed to facilitate the insertion and maintenance in the body of needles, catheters, and cannulas. Examples of such devices are disclosed in U.S. Pat. Nos. 4,397,641; 4,435,174; and 4,569,675. Invariably, however, these devices are used in conjunction with standard needles and catheters in an attempt to adapt same to meet this particular application. As far as applicants are aware, there has been no attempt to design a drug administration needle or cannula specially adapted to access implanted drug administration portals.